570 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



The temperature at which their different volatile products are 

 imperfectly separated from the crude petroleum, is much higher 

 than the boiling points given above, and must not be confounded 

 with them. Three temperatures of distillation I have given 

 approximately at a former meeting. 



This table contains all the different combinations of carbon and 

 hydrogen, commencing with pure hydrogen, then taking the 

 equivalent of carbon equal to half the hydrogen and increasing 

 both until an equal number of atoms is reached in the olefiant gas, 

 Avhich comes off at the end of the distillation, when also the par- 

 raffine is formed; the differences between the number of atoms of 

 both elements become therefore relatively smaller; when the coef- 

 ficients become for instance 1,000, we would have Cj^qoo ^1,001' 

 and finally they must become alike to all practical purposes; 

 when we develop olefiant gas, and have coke left, in case we con- 

 tinue the distillation to its extremity. Olefiant gas is in the rela- 

 tive quantities of its chemical contents much more like the par- 

 rafiine than like the condensable gaseous products comiug over at 

 the beginning of the distillation; it is also known that olifiant gas 

 requires very powerful pressure to be liquified, surpassing even 

 that required for carbonic acid and nitrous oxid. 



We may extend our series in the opposite direction, namely, mak- 

 ing the atoms of hydrogen less than those of carbon, and diminish 

 them till we have reached the pure carbons; the first number of 

 this series is woody fibre, of which the formula is C^g H^q O^^, 

 which we will divide by two for the sake of exhibiting the remarka- 

 ble progression of the series, in which I have made up the formula 

 after the quantitative analysis of the most reliable authorities. 



Table of the formulce and corresponditig names of the products of 

 the carbonization of wood. 



Formula. Name. 



Cg Hg O5 Fresh dry woody fibre. 



Cg Hg O4 Decaying wood. 



Cjr, Hg O3 Turf or peat. 



0^2 Hg O2 Lignite. 



Ci4 Hg O _ Cannel coal. 



CjQ Hg O Cherry coal. 



CjgHg Cake coal. 



C2 Hg - German blacksmith's coal. 



C22 Hg Anthracite coal. 



CiQo H - Lampblack. 



C4 H Charcoal. 



Cg Hq VmQ coal or carbon. 



